The amygdala is a region of the temporal lobe of most vertebrate brains that acts as a gatekeeper to the long-term memory, assigning priority to memories on the basis of the emotional intensity that accompanies them and in the process molding our emotional reflexes. Anyone who has been in combat or a car accident or read Dostoyevsky’s fictionalized account of his astonishing mental clarity in the minutes leading up to his near-execution should get the idea. But psychopaths, who suffer from a total deficit of amygdalal activity and the attendant empathy, never acquire such searing, indelible long-term memories. As a result, we learn in the British journalist Jon Ronson’s The Psychopath Test: A Journey Through the Madness Industry (Riverhead, 288 pages, $25.95), they have trouble relishing their pleasurable experiences for a sustained period of time. And since they derive great pleasure from inflicting suffering on others, they inevitably do it again and again, just to remember what it feels like.

This is not Mr. Ronson’s problem. To the contrary, he suspects he has been cursed with a preternaturally overactive amygdala, a condition that manifests itself in regular panic attacks, the occasional involuntary shriek and a recurring nightmare wherein a stranger chases after him yelling, “You’re a failure!”

A failure he is not, of course. His 2005 book The Men Who Stare at Goats sold millions of copies and in 2009 was adapted into a movie with George Clooney and Ewan McGregor that grossed nearly $70 million. That work also revolved around the amygdala, and the loosely coordinated efforts of American intelligence authorities over the years to learn how to hone in on its enemies’ amygdalas in the forms of psychological warfare endured by Dostoyevsky and Khalid Sheikh Mohammed and numerous detainees forced inexplicably to listen endlessly to a Matchbox 20 record. Psyops had experienced a broadly condemned rebirth within the United States’ vast international network of terror prisons, but between the psychedelic experimentations of MK-ULTRA, the CIA’s covert human research program, and the widespread waterboarding of suspected jihadists post-September 11, its progenitors had experimented on a herd of de-bleated goats in Fort Bragg, with limited but not unremarkable success: legend held that one soldier had actually succeeded in giving a goat a fatal heart attack simply by staring at it–hence the title.

The Psychopath Test treads on the less exotic ground of sanity, personality disorders and other pathologies, whether CEOs have the personality types of serial killers, the common fear of losing it and various other “madcap” subgenres of madness studies. Early on Mr. Ronson fixates on the disorder we know as psychopathy, which neurologists have traced to a severely inactive amygdala. He gingerly befriends a diagnosed psychopath, a Scientologist activist trying to get him released from prison, the man who invented the checklist of traits used to diagnose the young man, the man who invented the Diagnostic Statistical Manual of personality disorders and various other denizens of the “madness industry.” Chronically torn over the field’s myriad medical and ethical controversies, Mr. Ronson nevertheless remains uncharacteristically driven to prove a theory he airs at the outset: that his anxiety is evidence of an overabundance of amygdalal activity, making him the diagnostic opposite of a psychopath. (He is comforted to learn through painful shock treatments that he does indeed exhibit an above-average degree of anxiety.) It is an odd preoccupation, making the case that one is the diametric opposite of a psychopath; perhaps an ex-girlfriend could elucidate.

Perhaps in hopes of sparing us the personal hell of his own hyperactive amygdala, Mr. Ronson scrupulously avoids interacting with the amygdalal instincts of his readers. The Psychopath Test is so emotionally and psychologically untaxing to read that I began to suspect halfway through that I would finish it without “feeling” like I had actually read “a book.” I was right; my first thought upon shutting it was, “Bloody hell, was Blink even over this quickly?” I’m exaggerating with the “bloody hell” part, of course, in parroting Mr. Ronson’s lively conversational prose style. Like Malcolm Gladwell, he writes sentences with a “stickiness factor” that lodges his stories in a reader’s consciousness with minimal effort and no need for emotional investment.

But where Mr. Gladwell made his name writing about dog whisperers and coolhunters, Mr. Ronson’s favored subject material is conspicuously darker stuff. A recurring character in The Psychopath Test is a schizophrenic confined to the basement of her institution so as to minimize for fellow residents the olfactory imposition of her habit of smearing her own shit across the walls. In The Men Who Stare at Goats, we learn the U.S. government at one point dispatched a fleet of prostitutes to Guantánamo Bay to taunt the more devout prisoners by, among less innovative humiliations, rubbing menstrual blood on their faces; the walls of Abu Ghraib are smeared with human brains. But Mr. Ronson dutifully follows such anecdotes with joking asides, choosing to lavish tangential passages instead on the television shows he watches in his hotel room in Sweden, where he gleefully commences The Psychopath Test by remarking that “the smell of a newly cleaned rental car . . . never fails to bring back happy memories of past sleuthing activities.”